1. Field of the Invention
The present invention relates to a piezoelectric ceramic composition and an oscillator.
2. Related Background of the Invention
Since piezoelectric ceramic composition has a piezoelectric effect which generates electric polarization on being subjected to external pressure, and has an inverse piezoelectric effect which generates strain on being subjected to an external electric field, it is used as a material to perform interconversion between electric energy and mechanical energy. Owing to these effects, such piezoelectric ceramic composition has been used in varieties of products such as resonator (oscillator), filter, sensor, actuator, ignition element, and ultrasonic motor.
An example of the piezoelectric ceramic composition has been known, which is characterized in ceramic filter and the like utilizing a third harmonic wave of thickness longitudinal vibration is a piezoelectric ceramic composition prepared by adding Mn and Cr to a lead titanate system obtained by substituting a Pb part of PbTiO3 with La to give a composition expressed by the general formula of Pb1−3y/2LayTiO3+z.{(1−x)MnO2+(x/2).Cr2O3}, (o<x<1 and 0<z≦5% by weight), (Japanese Unexamined Patent Publication No. H5-139824).